User manual

4. Signal Cable Options
Balanced cable configuration is the preferred
option, however unbalanced connection is possible.
Diagrams 2 and 3 illustrate the signal cable
connections required for each option. Balanced
(XLR to XLR) connection offers lower noise and
better immunity to “hum” pick-up. Unbalanced
(XLR to Phono or Two Pole Jack) connection
carries risk of hum caused by multiple signal earths.
Hum problems resulting from unbalanced
connection may be reduced by making ONE of the
following modifications to the signal cable
connections: If the driving preamplifier (or desk) is
“double insulated” (i.e. has no mains earth),
disconnect the signal cable screen at the RCA Phono
plug end. Alternatively, disconnect the signal cable
screen at the XLR end.This second option will make
the source the reference signal earth.
5. Operation
Diagram 4 illustrates the connection and control
panel. Each feature is described below.
5.1 Mains Inlet: The supplied mains power lead
(appropriate to the local territory) should be
connected here. Ensure that the mains voltage
specified on the panel corresponds with the
local supply.
5.2 Power Switch: Switches on the monitor.When
switched on the indicator on the panel will
illuminate.
5.3 Fuseholder: Should a monitor fail to switch on
when the power switch is operated the fuse
should be inspected. Lift out the fuseholder
cover using a small flat-blade screwdriver,
remove the fuse and inspect it for damage. If
required, a replacement fuse should be fitted. It
should be stressed however that fuses most
often fail only because of a serious electrical
fault. If this is the case then simply replacing the
fuse will only result in another fuse failure.The
monitor should be returned to ATC if a second
fuse fails.
5.4 Input Socket: The audio signal cable should be
connected here. Balanced or unbalanced cables
may be used (See Section 3).
5.5 Bass Boost (SCM “Pro” only): Provides up to
6dB of gain in the region of 40Hz. Use a small
flat blade screwdriver to access the control.Adds more warmth and energy to
the lower frequencies in music, at the expense of accurate transient
reproduction. Note: Adjusting the bass boost without the ability to recalibrate
may leave a pair of monitors unmatched.
5.6 Level Trim (SCM “Pro” only): Provides access to an internal control that enables
adjustment of input sensitivity. Use a small flat blade screwdriver to access the
control. As supplied, monitors are calibrated to an input sensitivity of 1V.
Note:Adjusting the sensitivity without the ability to recalibrate will leave a pair
of monitors unmatched.
Due to the nature of the electronics in ATC active loudspeakers it is quite normal
for a sound to be heard from the speaker when the power is applied or
disconnected. The noise heard will not damage the speaker and is quite normal.
Although ATC uses the highest-grade components, a different noise may be heard
from each speaker due to slight tolarance variations in the amplifier components.
Installation cont’d
4
SCM50/100/150ASL
Diagram 4 - connection and control panel
Bass Boost
(SCM “Pro” only)
Level Trim
(SCM “Pro” only)
6. Listening
The ear and brain tend to interpret distorted sound as loudness and thus
underestimate the actual level of undistorted sound.The SCM50, 100 and 150, like
all ATC monitors, demonstrates very much lower levels of distortion than
conventional systems of a similar size and it is therefore advisable to begin listening
at an artificially low level and carefully increase the volume. It is also possible for the
SCM50, 100 or 150 to produce sufficient sound pressure levels for your ears
themselves to become a source of distortion and make the sound appear harsh.Any
audible distortion indicates that either the system or your ears are being overloaded
and that the volume level should be reduced.